Technical Field
Certain embodiments of the invention relate to cryogenic refrigerators that employ a high-pressure working fluid supplied from a compression apparatus to cause Simon (adiabatic) expansion and bring about cooling at cryogenic temperatures.
Description of Related Art
The Gifford-McMahon (GM) refrigerator is one example of refrigerators known to generate cryogenic temperatures. With GM refrigerators, inside a cylinder a displacer is reciprocated to change the volume of expansion space. Selective connecting, in response to the change in volume, of the discharge side and intake side of the refrigerator compressor with the expansion space expands the working fluid in the expansion space. The cooling therein brought about refrigerates the refrigeration target.